FIG. 3 illustrates a schematic diagram of a multistage axial flow compressor. A compressor 1 includes a rotating rotor 22 to which multiple rotor blades 31 is fitted, and a casing 21 to which multiple stator 34 is fitted, and has an annular flow passage formed by the rotating rotor 22 and the casing 21 inside. The rotor blades 31 and the stator vanes 34 are alternately arranged in an axial direction thereof, and each rotor blade and each stator vane configure one stage. An inlet guide vane 33 (IGV) for controlling an inlet flow, rate is disposed upstream of an initial rotor vane row. Also, a last-stage stator vane 35 and exit guide vanes (EGV) 36, 37, which are stator vanes, are disposed downstream of a last-stage rotor blade 32. FIG. 3 illustrates a configuration in which two exit guide vane rows are disposed in the axial direction.
An inlet air of the axial flow compressor is decelerated and compressed by the respective vane rows into a high-temperature and high-pressure airflow while passing through the annular flow passage. A pressure increase (corresponding to a vane row load) of each vane row is determined according to a set angle of the vane row and an operating state. There is a need to ensure an aerodynamic performance and reliability of the vane rows even in the operating state where the vane row load is highest.
Japanese Unexamined Patent Application Publication No. 2002-61594 discloses a load control system for a compressor which controls the respective stator vanes as independent variable vanes, and averages the loads of the respective stages. However, Japanese Unexamined Patent Application Publication No. 2002-61594 fails to disclose a load distribution of the stator vanes situated on a rear stage side of the axial flow compressor.